1. Field of the Invention
Embodiments of the invention generally relate to a transportable (i.e., mobile) fluid cracking catalyst injection system.
2. Background of the Related Art
Fluid catalyst cracking units (FCCU) are commonly used in petroleum refining to break long chain hydrocarbons present in crude oil and to adjust the product mix recovered at the distiller. A main catalyst is generally introduced into the FCCU by a catalyst injection system which periodically meters out catalyst for injection over a predefined period of time. Such injection systems are available from Intercat, Inc., located in Sea Girt, N.J. Other examples of conventional injection systems are described in U.S. Pat. No. 5,389,239, issued Feb. 14, 1995, which is incorporated by reference in its entirety.
In addition to the main catalyst, it is often beneficial to inject other catalysts into the FCCU to further influence the refining process. For example, some catalyst are formulated to control certain types of emissions, such as the amount of sulfur- and nitrogen-containing compounds present in refinery emissions. Other catalysts may be formulated to influence the product mix recovered in the distiller. For example, catalyst may be formulated to produce more diesel fuel relative to gasoline or to increase the amount of liquid petroluem gas produced, among others.
FIG. 1 is a simplified schematic of one embodiment of a conventional fluid catalytic cracking system 130. The fluid catalytic cracking system 130 generally includes a fluid catalytic cracking (FCC) unit 110 hard piped to a catalyst injection system 100, an oil feed stock source 104, an exhaust system 114 and a distillation system 116. One or more catalysts from the catalyst injection system 100 and oil from the oil feed stock source 104 are delivered to the FCC unit 110, The oil and catalysts are combined to produce an oil vapor that is collected and separated into various petrochemical products in the distillation system 116. The exhaust system 114 is coupled to the FCC unit 110 and is adapted to control and/or monitor the exhausted byproducts of the fluid cracking process.
The catalyst injection system 100 includes a main catalyst source 102 and one or more additive sources 106. The main catalyst source 102 and the additive source 106 generally mounted on a concrete foundation or pad 180 and are hard piped to the FCC unit 110 by a process line 122. A fluid source, such as a blower or air compressor 108, is coupled to the process line 122 and provides pressurized fluid, such as air, that is utilized to carry the various powdered catalysts from the sources 102, 106 through the process line 122 and into the FCC unit 110.
A controller 120 is utilized to control the amounts of catalysts and additives utilized in the FCC unit 110. Typically, different additives are provided to the FCC unit 110 to control the ratio of product types recovered in the distillation system 116 (i.e., for example, more LPG than gasoline) and to control the composition of emissions passing through the exhaust system 114, among other process control attributes.
As these injection systems are typically supported on a separate foundation and hard pipe connected to the FCC unit, the flexibility of the refiner to rapidly add an additional catalyst injection system is very limited. For example, the time required to plan and install a new catalyst injection system may prevent the refiner from taking advantage of market conditions favorable to a certain product mix not achievable using catalyst injection systems currently coupled to the FCCU. The difficulty in providing quick process adjustment through the injection of additional catalyst in a new catalyst injection system also hampers the ability of the refiner to quickly adjust refinery emissions due to changes in regulations, differences in the chemical make-up of crude oil or process equipment failure. Furthermore, as catalyst injection systems are expensive to install, it is undesirable to have unused catalyst injection systems stationed online as a precaution against any unanticipated need for process control.
Therefore, there is a need for a catalyst injection system which enhances process flexibility.